During the field visits it was observed that riparian vegetation plays a determinant role in species composition. As the summer arrives there will be a great variation in temperature during the day and night. The rain fed streams especially in the eastern part of the study area shows considerable reduction in the flow. The less flow makes them sensitive to any variation in atmospheric temperature. The sparse riparian vegetation further worsens the condition by directly exposing the stream to sunlight. During this condition, the habitats for most of the fishes become unsuitable and they move to those places where there is considerable vegetation along the bank, which will maintain the stream temperature. The summer sampling of these hill streams confirmed these facts as no fishes other than Danioaequipinnatus and Aplacheilus lineatus were found in open areas. Where there is conopy cover, both species-wise and individual fish were concentrated However, this effect was comparatively less in the western part of the area as there is more canopy over, more flow and lesser temperature.